Data display system



Nov. 10, 1970 J. K. CRAWFORD ET AL 3,540,033

DATA DI SPLAY SYSTEM HEXADECIMAL DECODER HEXADECIMAL DECODER I (PARTIAL) (FULL) DATA BITS 0-3 DATA BITS 4-7 United States Patent O 3,540,033 DATA DISPLAY SYSTEM John K. Crawford, La Grange, Donald C. Croll, Pleasant Valley, John C. Hulsizer, La Grange, Frank T. Kendall, Poughkeepsie, and George B. Schaefier, In, La Grange, N.Y., assignors to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed Dec. 28, 1967, Ser. No. 694,313 Int. Cl. G08b 11/00 US. Cl. 340-324 Claims ABSTRACT OF THE DISCLOSURE A data display has a matrix of passive indicia provided with coordinate indicator lights arranged in cross configuration, medially of the field of indicia for close correlation with an indicium to be indicated. Part of the input data is decoded to operate a light in one coordinate axis, and the rest is decoded to operate a light in the other axis. The matrix and decoder can be limited to handling only certain values, and a switch can be provided to connect the indicator lights of one axis as data bit lights for reading other values.

BACKGROUND OF THE INVENTION A large variety of equipments require some sort of display capability for conveying data, which may be indicative of the output of the equipment or of some condition in the operation of the equipment, to a human operator or observer. In many cases the information is present in the equipment in binary form, and one function of the display is to present that information in more easily understandable fashion.

Many data processing systems have so-called bit lights which indicate, when on, a one value and when off a Zero condition of the corresponding order of a multiplace binary number. These bit lights can be grouped by threes or fours so that an experienced operator can read them at a glance in octal or hexadecimal form, However, there are many cases in which it is desirable that the display be readable by a person not familiar with such coding forms, and moreover, it is desirable that the display be able to show specially coded letters and symbols directly, without need for employment of a code conversion chart.

Accordingly, the prior art has developed a wide variety of displays which, when operated by a suitable decoder and control mechanism, can present the desired decoded value directly to the operator. Such prior art displays include rotary number wheels, segmental character displays, cathode ray tube displays and electroluminescent and other matrix displays, to name but a few examples. Such prior art displays, although very useful in appropriate circumstances, fail to provide a data output for those cases where cost and size are critical factors and yet a wide variety of characters are to be decoded and presented in easily readable form. Another class of prior art displays involves the use of a map or the like whereby movable lights or movably directed light beams can indicate a position on the map while using fewer light elements than there are positions on the map. Again, such mechanical arrangements involve the use of costly apparatus and are, of course, prone to wear and breakdown.

SUMMARY OF THE INVENTION The present invention provides a display whereby a large number of characters, for example one hundred, can be indicated by operation of a relatively small number, for example twenty, of inexpensive incandescent lights. Moreover, economies in decoding and driving circuitry are effected, not only because the lights themselves require no special controls, but also because their arrangement, in eifect, provides a kind of matrix decoder operation in a simplified manner.

In accordance with one aspect of the invention, the display comprises an array of indicia corresponding to the characters to be displayed, together with coordinate indi cators suitably energizable in accordance with the decoded value of input data so as to provide a directly readable data display. In accordance with another aspect of the invention, the coordinate axes on which the indicators are aligned are placed in cross configuration, medially of the field of indicia so as to facilitate rapid and accurate reading of the display. Additional features of the invention reside in compression of the code set as displayed reducing the size of the display, and provision of switch means for optionally connecting input data signals directly to elements of the display in undecoded form.

Accordingly, a principal object of the invention is to provide an improved data display system particularly adapted to those employments wherein a large variety of characters are to be presented but wherein size and cost considerations exclude the use of character generator systems or the like.

Another object of the invention is to provide a display as aforesaid having a multiplicity of effective output positions with minimum driving circuitry and the utmost mechanical simplicity;

Still another object of the invention is to provide a display as aforesaid which is easily readable by persons having no experience with special code formats.

Yet another object of the invention is to provide an improved display as aforedescribed which is quickly adaptable to a variety of character sets and which, moreover, can function in hit light fashion when required.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation of a display system constituting one preferred embodiment of the invention;

FIG. 2 is a chart of code assignments for operation of the display of FIG. 1; and

FIG. 3 is a logic diagram of a decoder arrangement for inclusion in the system of FIG. 1, for operation in accordance with the code assignment shown in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The display system shown in FIG. 1 includes a character bearing plate 20, which may be a passive element such as a sheet of metal having painted or engraved thereupon an array of passive indicia 22-22 corresponding to the characters which are to be indicatable by the display, As shown, some of the characters are single such as the letter A, etc., and others are composite such as the group called SPC or the arrangement of LZ over START, but each single or composite character indicium occupies a discreet position in a rectangular grid coordinate arrangement.

Arranged in cross configuration, medially of the plate 20 and the array of indicia thereon, are a pair of rows of indicator lights 24, 26, row 24 being disposed in the horizontal or X direction while row or column 26 is vertically disposed, in the Y coordinate direction.

Drive circuitry is provided to operate the X and Y lights in a coordinate manner for indicating readout of one of the passive indicia 22. For example, if the letter N is to be indicated, the coordinate X and Y lights 28, 30 will be illuminated, and the operator will trace visually to the intersecting position at which the character N is inscribed on the passive plate 20. Suitable drive circuitry for this purpose is provided, and in the illustrated embodiment of the invention comprises a register 32, which may be an output register of a data processing apparatus, for example, having a capacity of eight binary data bits (bit positions zero through seven). This capacity amounts to two four-bit bytes, each having a possibility of sixteen values usually identified in hexadecimal code as 0, l, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E,,F. In the ensuing discussion it is important to note that the letters A through F in hexadecimal code are not to be confused with the alphabetic characters A through F appearing in the display.

In the illustrated arrangement, bit positions 0, 1, 2, 3 are connected via a cable 34, a normally conditioned parallel gate circuit 36, and cable 37 to a decoder circuit 38 which will be described in further detail hereinafter but which provides a unique output in cable 40 connected to a corresponding one of the Y coordinate lights 26 for each of the code conditions of bit positions through 3 which are valid for the display.

In like manner, cable 42 connects bit positions 4, 5, 6, 7 of the register 32 through a normally conductive gate arrangement 44 and cable 45 to a decoder 46, which delivers via cable 48 energization to a unique one of the X coordinate lights 24 in accordance with each valid code combination for bit positions 4 through 7 in the data of register 32. Since, in the illustrated embodiment of the invention, there are ten X axis lights and ten Y axis lights, it will be understood that the cable 40 contains ten circuits and the cable 48 contains ten other circuits.

Since the four-bit byte delivered to decoder 38 could yield sixteen possibilities and the byte consisting of bits 4 through 7 could decode into another sixteen possibilities, a full X-Y matrix, all of the possibilities would yield two hundred and fifty-six outputs. However, in the case of many employments of the display this is an unnecessarily large number, and, in fact, one hundred outputs provided by a ten by ten matrix is ample. Nevertheless it is sometimes desirable to be able to read the actual content of register 32 even though that content might constitute a code which is outside the code set for which the hundred character display is designed.

In the illustrated embodiment of the invention this ability is provided by alternate energization of eight of the circuits of cable 48 through cable 50 connected thereto. Conveniently, the eight circuits of cable 50 can be connected to the first eight circuits of cable 48 so that the horizontally arranged or X axis lights 24 which are juxtaposed to the characters 0 through 7 on plate 20 can function as bit lights for operation in response to data bits 0 through 7 in register 32. For this purpose, bits 0-3 in register 32 are connected via cable 52 and bits 4-7 via cable 54 to a normally non-conditioned or nonconducting gate circuit arrangement 56 which, when conditioned, connects these outputs to corresponding circuits in cable 50. For rendering gate 56 conductive and at the same time deconditioning gates 36 and 44, control circuitry is provided which may comprise, for example, a push button 58 for connecting a suitable source of power from terminal 60 to the conditioning control line 62 of gate circuit arrangement 56 and, through inverter circuitry 64 to the control lines 66, 68 of gate circuitries 44 and 36. Accordingly, operation of push button 58 disconnects the decoders 38 and 46 from the system and establishes direct connection from the data bit outputs of register 32 to the corresponding leftmost eight lights of the horizontal row of indicator lights 24.

It will be understood that the desirability of providing the above-described bit light facility in the display will depend on the characteristics and usage of the equipment A to which the display of the invention may be applied. Moreover, in those equipments wherein register 32 would have a ninth bit position (bit position 8) for a parity or check bit, this position can also be wired to the display under control of gate circuitry 56, in such case to the ninth light in row 24.

As noted above, the eight binary bits of information in register 32 could signify 256 discrete values, since bit positions 0 through 3 constitute a hexadecimal byte having sixteen values and bit positions 4 through 7 constitute another byte having another sixteen values. It is possible to construct an arbitrary code chart assigning any character to any of these 256 possibilities. For example, one code system used in the data processing industry and known as Extended Binary Coded Decimal Interchange Code or EBCDIC can be used for the standard character set of the code, and, superimposed on this, special characters such as LZ seen in the display of FIG. 1 can be added in positions of the character chart which are not used in the regular code chart but which are left empty for such special purposes. Such a modified EBCDIC code set is illustrated in FIG. 2. As shown, bits 0 through 3 of register 32, FIG. 1, have conventional hexadecimal value of 0 through F, while bits 4 through 7 decode into another hexadecimal number 0 through F. The combination of these two numbers defines 256 possibilities, indicated by the intersections of the matrix chart. For example, the hexadecimal number D of the first hexadecimal number (identified at the top of the diagram) in conjunction with the hexadecimal number 2 of the second bit group (identified at the left border of the chart) together define the character K which is to be read out from the display.

Referring again to FIG. 1, all that is necessary to indicate a K is that the seventh light from the bottom of the Y axis and the third light from the left of the X axis be illuminated; then the operator completes the decoding, so to speak, by visually tracing to the intersection of the row and column defined by those two lights, at which is found the passive indicium K. In order to reduce confusion between reference numbers and characters of the display in the illustration of FIG. 1, the X and Y lights 24, 26 are not individually numbered, instead they will be referred to in the ensuing discussion by the hexadecimal number or hexadecimal number group which they represent. Thus, the third light from the left in the X axis is identified as light 2+A and the seventh light from the bottom of the Y axis is identified as light D, as indicated by the explanatory legend at the top and left side of the figure. It will be seen that these hexadecimal values are not in strict sequential order for both axes and that at least some of them are double. This reordering of the sequence is for the purpose of arranging the EBCDIC coded values in a familiar sequence on the display, and the combining or ORing of certain values such as 2+A results from compression of the code chart so as to close empty areas in the same, thereby providing a compact display.

The relationship of the code assignments of FIG. 2 to the placement assignments of FIG. 1 can be appreciated by reference to FIG. 3, wherein the decoding logic 38, 46 of FIG. 1 is further illustrated. As seen in FIG. 1, data bits 0, 1, 2, 3 from register 32 must decode into individual outputs for operation of the vertical column or axis of lights which are identified as 4, 5, 6, 0+7, F, E, D, C, 8 and 1+3. These lights are shown at the left top of FIG. 3, labeled in the aforedescribed manner. These identifications are also the hexadecimal values of data which will operate the lights. It should be noted, however, that of the sixteen number hexadecimal set, the numbers 2, 9, A and B are not used and need not be decoded from the data byte delivered by cable 37.

For simplicity of illustration, conventional hexadecimal decoder circuitry is indicated by a box 70', but it will be understood that the decoding may be only partial because certain of the outputs, as aforedefined, are not needed. Accordingly, if a decoder is built especially for the purpose of the display, certain of its circuits may be omitted. The decoder itself can be of any usual or conventional kind such as a tree decoder or a matrix decoder illustrated in the text Arithmetic Operations in Digital Computers, by R. K. Richards, D. Van Nostrand Company, Inc., Princeton, NJ. (1955), pages 72-73, with only so much of the decoder omitted as plays no role in the production of the needed outputs. It is then a simple matter to connect the outputs of the hexadecimal decoder 70 to the desired conductors in cable 40. For example, the output of the hexadecimal value 4 of decoder 70 is connected directly to the conductor of cable 40 leading to light bulb number 4, and decoder outputs 5 and 6 lead directly to the conductors operating light bulbs 5 and 6, respectively. However, it will be noted that in FIG. 1 the next light bulb is operated by either hexadecimal value 0 or hexadecimal value 7. Accordingly, output line 0 of the decoder 70 and output line .7 thereof are connected together by an OR junction 72, the output of which is connected to the conductor of cable 40 for bulb 0+7, and so on. The OR 72 may be a simple conductor junction, or it may be a diode OR or the like, depending on the requirements of the circuitry employed, as will be readily understood. As shown in the figure, the outputs F, E, D, C and 8 of decoder 70 are connected via conductors of cable 40 directly to the correspondingly identified light bulbs, while decoder 70 outputs 1 and 3 are ORd to the cable 40 .condutcor operating light 1+3.

Operation of decoding logic 46 is similar to that of logic 38 with the exception that it employs a full sixteen output hexadecimal decoder 74 (which, again, may be of one of the known kinds such as shown in the above cited text) and has six ORd outputs to cable 47. Thus although the code set of FIG. 2 of the illustrated system requires all of the output values of register 32 bits 4 through 7, it also allows for more compression, or ORing, so that only ten light bulbs are needed for the corresponding X axis of the display.

The indicator lights 24, 26 shown are simple incandescent bulbs, requiring a minimum of complexity in the driving circuits. Of course it will be understood that if the decoder outputs lack the power or characteristics for operating the kind of indicators chosen, relays and/ or amplifiers or the like can be inserted in the circuits.

The character indicia 22 are termed passive since they require no direct power. Of course they can be of any desired construction and can receive light from the active indicators 24, 26, if desired. Since the character indicia are simple, the panel 20 carrying them can be replaced easily to provide a different character set. Similarly, the wiring of FIG. 3 can be altered readily to provide a different character indicium orientation or to accommodate a difierent character code set makeup.

Accordingly, while the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In a display system,

data input means for numerical information,

circuit means responsive to said data means to provide first and second subset data derived from said information,

and matrix means for relating said subset data for identifying a unique display value,

said matrix means comprising:

a column and a row of active visual indicators arranged to define coordinate axes,

and an array of passive indicia juxtaposed to said indicators in a coordinate field corresponding to the positions of the same,

and selective means including decoder means connecting said active indicators to said circuit means for operation in accordance with said subset data.

2. A system in accordance with claim 1, wherein:

said row and said column of indicators are disposed in cross configuration medially of said field.

3. A system in accordance with claim 2, wherein:

at least one of said subset data comprises ordered data having a greater number of possible values than there are active indicators in the corresponding axis,

and at least two of the outputs of said decoder means are connected to drive the same indicator alternatively,

whereby the display of data is compressed.

4. A system in accordance with claim 3,

further including alternative circuit means for connecting at least one of said column and row of indicators directly to said data input means.

5. A system in accordance with claim 1, wherein:

at least one of said subset data comprises ordered data having a greater number of possible values than there are active indicators in the corresponding axis,

and at least two of the outputs of said decoder means are connected to drive the same indicator alternatively,

whereby the display of data is compressed.

6. A system in accordance with claim 5,

further including alternative circuit means for connecting at least one of said column and row of indicators directly to said data input means.

7. A system in accordance with claim 1,

further including alternative circuit means for connecting at least one of said column and row of indicators directly to said data input means.

8. A system in accordance with claim 2,

further including alternative circuit means for connecting at least one of said column and row of indicators directly to said data input means.

9. A system in accordance with claim 2, wherein:

said numerical information comprises first and secon four-bit binary bytes,

and said first and second subset data comprises first and second hexadecimal values respectively derived from said bytes by said circuit means and said selective means.

10. A system in accordance with claim 2, wherein:

said active indicators comprise incandescent light bulbs.

References Cited UNITED STATES PATENTS 10/1965 Jacob 340-366 x 8/1968 Abramson et a1. 340 s24 X US. Cl. X.R. 

